It is known in the field of vehicle technology to control hydraulic pressure of a brake installation in an indirect manner by equipping a brake pedal with a sensor, or a plurality of sensors whose detected signals are used in actuation of the brake pedal for the purpose of controlling the brake installation.
For example, U.S. Pat. No. 8,326,505 B2 describes a control system for an electromechanical brake system provided with actuation elements, which are designed to actuate brake elements for the purpose of exerting a braking action. The control system has a control stage for the purpose of controlling the braking action on the basis of a brake reference signal. The control stage comprises a model-based, predictive control block, in particular of a generally predictive, self-adaptive controller type, which operates on the basis of a control variable that represents the braking action. The control system further has a model identification stage, which determines parameters that identify a transmission function of the electromechanical brake system, and a regulating stage, which determines an optimum value of parameters of the control system inherent to a controller using a value of identification parameters. A braking force requested by a driver is ascertained by provided sensors, which detect, for example, an angle and movement speed of the brake pedal.
U.S. Pat. No. 5,230,549 A further describes a motor vehicle brake system comprising braking-force-generating apparatuses, which are mechanically separated from a brake pedal and can be controlled to exert braking forces on wheels in response to a detected pressing-down of the brake pedal. The brake system has a sensor for detecting a displacement of the brake pedal and a sensor for detecting a force exerted on the brake pedal. The braking-force-generating apparatuses are controlled by a controller based on a detected displacement of the brake pedal and a detected force applied to the brake pedal.
The signals that are detected when the brake pedal is actuated can also be used for the purpose of improving safety.
DE 10 2014 211 008 A1, for example, describes a sensor apparatus and a method for executing or boosting an autonomous build-up of brake pressure in a brake system by an active, braking-force booster. Reliable options for early recognition of brake pedal blocking during an autonomous, or partially autonomous build-up of brake pressure in at least one-wheel brake cylinder of a brake system is intended to be provided. The sensor apparatus for a brake system comprises an active braking force booster designed for executing, or boosting, an autonomous, or partially autonomous build-up of brake pressure, has an electronics device, which, at least during the autonomous, or partially autonomous build-up of brake pressure that is executed, or boosted, by means of the active braking force booster, is designed to output at least one activation signal to a warning display apparatus, and/or a warning tone output apparatus, and/or at least one control signal to the active braking force booster taking into account at least one deformation variable with respect to a deformation of the active braking force booster, said variable being set by the sensor apparatus or provided externally, and/or a traction exerted on a brake pedal of the brake system and causing the deformation, in order to control said active braking force booster in a safety mode at least for a prescribed first time interval, or to interrupt said active braking force booster at least for a prescribed second time interval.
JP 5402897 B2 further describes an apparatus for determining faulty operation of a gas pedal during intended actuation of a brake pedal. A pressure-sensitive sensor is, or a plurality of pressure-sensitive sensors are, provided on a bottom side of a gas pedal in a region of the gas pedal that is close to the brake pedal. When a pressure force on the gas pedal is detected by means of the pressure-sensitive sensor during actuation of the brake pedal by an instance of slipping off, actuation of the gas pedal is assessed as a faulty operation by a control unit. As a result thereof, the faulty operation of the gas pedal can be determined before an arm of the gas pedal is moved in a rotating manner.
It is further known to exert mechanical, retroactive effects on a brake pedal of a vehicle in order to prevent disadvantageous influences of pedal feel for a driver, for example in the case of a regenerative braking process. When the pedal feel does not correspond to an expectation of the driver, this can lead to excessive or insufficient braking, as a result of which driving safety is negatively influenced.
For example, KR 101447467 B1 proposes a pedal simulator for an active brake apparatus. The pedal simulator is installed in a main brake cylinder and receives fluid pressure, which corresponds to a pedal force of an operator. The pedal simulator serves to make it possible for an operator to sense pressing of a pedal. The pedal simulator comprises a simulator block in which an oil bore, which is connected to the main cylinder, is formed on an upper part. Furthermore, a bore is provided on an inside, which is connected to the oil bore; a connected damping housing, which is provided to seal off a lower end of the bore; a first reaction force unit, which is provided in the bore, which is pressurized by oil fed by the main brake cylinder and provides a reaction force; and a second reaction force unit, which is borne by the damping housing and is compressed when the first reaction force unit is pressurized and delivers the reaction force, wherein the second reaction force unit is elastically deformed in order to cover the upper end of the damping housing.
In addition to the use of classic switches and/or pressure sensors, it is known to use pressure sensors that are easily deformable in connection with vehicle pedals.
U.S. Pat. No. 6,556,149 B1, for example, describes switches and joysticks comprising a non-electrical, deformable, pressure sensor. Switches and joysticks comprise user-friendly, two-position and multi-position switches, including simple on/off and variable switches like dimmers, for example. The switches operate in accordance with the principle of detecting a position of a switching arm that can be grasped by a user, a part of said switching arm bearing on a pressure-sensitive pad. The pad is a deformable material, which recognizes and localizes pressure on the pad by emitting an energy wave, for example in the form of light, into a matrix of the pad, and detecting an intensity thereof. Since the pad is compressed locally, the intensity of the energy wave in a region around compression increases. The position of a switching arm can thus be recognized and information transmitted to a central processing unit for further processing.
Furthermore, U.S. Pat. No. 6,556,149 B1 proposes a deformable, pressure sensor on a vehicle pedal, such as a brake pedal, for example. The vehicle pedal is equipped with a deformable pad on a user-contact face, said pad being connected to one or more emitter/detector pairs. In this case, the pad is compressed by pressure from a foot of a user against the pedal, and a corresponding proportional signal is transmitted to a control unit.
In view of the prior art described, the field of sensor systems in connection with pedals of vehicles leaves room for improvement.